Method for triggering power headroom reporting in a dual connectivity system and a device therefor

Abstract

A method for a User Equipment, UE, operating in a wireless communication system, includes triggering power headroom reports (PHRs), in a first Medium Access Control (MAC), entity and a second MAC entity when a first type event occurs in the second MAC entity, wherein the UE is configured with the first MAC entity corresponding to a first base station and the second MAC entity corresponding to a second base station for a radio bearer; triggering a PHR in the second MAC entity only, when a second type event occurs in the second MAC entity, wherein the first type event includes: there are uplink resources allocated for transmission on any cell of the second MAC entity and a required power backoff for the any cell of the second MAC entity has changed more than a threshold, or wherein the first type event includes: there is uplink transmission on any cell of the second MAC entity and a required power backoff for the any cell of the second MAC entity has changed more than a threshold.

What is claimed is: 
     
         1 . A method for a network operating in a wireless communication system, the method comprising:
 transmitting, to a user equipment (UE), information for configuring a first Medium Access Control (MAC) entity of the UE for communication with a first base station, and a second MAC entity of the UE for communication with a second base station;   receiving, from the UE, power headroom reporting (PHR) triggered in the first MAC entity and the second MAC entity, based on a first type event occurring in the first MAC entity; and   receiving, from the UE, PHR triggered in the first MAC entity only, based on a second type event occurring in the first MAC entity,   wherein the first type event occurring in the first MAC entity comprises: 
 (1) (i) there are uplink (UL) resources allocated for transmission on a serving cell of the first MAC entity or (ii) there is a physical uplink control channel (PUCCH) transmission on the serving cell of the first MAC entity, and 
 (2) a required power backoff due to power management for the serving cell of the first MAC entity has changed more than a threshold since a last transmission of a PHR when the first MAC entity had UL resources allocated for transmission or PUCCH transmission on the serving cell of the first MAC entity. 
   
     
     
         2 . The method according to  claim 1 , wherein the second type event occurring in the first MAC entity comprises at least one of the following events: (i) a periodicPHR-Timer of the first MAC entity expires, or (ii) upon configuration or reconfiguration of the power headroom reporting functionality for the first MAC entity by upper layers, which is not used to disable the power headroom reporting functionality. 
     
     
         3 . The method according to  claim 1 , further comprising:
 receiving a first PHR MAC Control Element (CE) generated at the first MAC entity and a second PHR MAC CE generated at the second MAC entity based on the PHR being triggered in the first MAC entity and the second MAC entity.   
     
     
         4 . The method according to  claim 1 , further comprising:
 receiving, from the first MAC entity of the UE, a third PHR MAC CE generated at the first MAC entity based on the PHR being triggered in the first MAC entity only.   
     
     
         5 . The method according to  claim 1 , further comprising:
 receiving, from the first MAC entity of the UE, a fourth PHR MAC CE generated at the first MAC entity based on PHR being triggered in the first MAC entity according to the first type event occurring in the second MAC entity of the UE.   
     
     
         6 . The method according to  claim 1 , further comprising:
 receiving, from the first MAC entity of the UE, a PHR MAC CE generated at the first MAC entity based on the PHR being triggered in the first MAC entity,   wherein the PHR MAC CE comprises information regarding a difference between (i) a nominal UE maximum transmit power on a cell of the first MAC entity, and (ii) an estimated power for uplink transmission on the cell of the first MAC entity.   
     
     
         7 . A network configured to operate in a wireless communication system, the network comprising:
 at least one transceiver;   at least one processor; and   at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations comprising:
 transmitting, to a user equipment (UE), information for configuring a first Medium Access Control (MAC) entity of the UE for communication with a first base station, and a second MAC entity of the UE for communication with a second base station; 
 receiving, from the UE, a power headroom reporting (PHR) triggered in the first MAC entity and the second MAC entity based on a first type event occurring in the first MAC entity; and 
 receiving, from the UE, PHR triggered in the first MAC entity only, based on a second type event occurring in the first MAC entity, 
 wherein the first type event occurring in the first MAC entity comprises: 
 (1) (i) there are uplink (UL) resources allocated for transmission on a serving cell of the first MAC entity or (ii) there is a physical uplink control channel (PUCCH) transmission on the serving cell of the first MAC entity, and 
 (2) a required power backoff due to power management for the serving cell of the first MAC entity has changed more than a threshold since a last transmission of a PHR when the first MAC entity had UL resources allocated for transmission or PUCCH transmission on the serving cell of the first MAC entity. 
 
   
     
     
         8 . The network according to  claim 7 , wherein the second type event occurring in the first MAC entity comprises at least one of the following events: (i) a periodicPHR-Timer of the first MAC entity expires, or (ii) upon configuration or reconfiguration of the power headroom reporting functionality for the first MAC entity by upper layers, which is not used to disable the power headroom reporting functionality. 
     
     
         9 . The network according to  claim 7 , wherein the operations further comprise:
 receiving a first PHR MAC CE generated at the first MAC entity and a second PHR MAC CE generated at the second MAC entity based on the PHR being triggered in the first MAC entity and the second MAC entity.   
     
     
         10 . The network according to  claim 7 , wherein the operations further comprise:
 receiving, from the first MAC entity of the UE, a third PHR MAC CE generated at the first MAC entity based on the PHR being triggered in the first MAC entity only.   
     
     
         11 . The network according to  claim 7 , wherein the operations further comprise:
 receiving, from the first MAC entity of the UE, a fourth PHR MAC CE generated at the first MAC entity based on the PHR being triggered in the first MAC entity according to the first type event occurring in the second MAC entity of the UE.   
     
     
         12 . The network according to  claim 7 , wherein the operations further comprise:
 receiving, from the first MAC entity of the UE, a PHR MAC CE generated at the first MAC entity based on the PHR being triggered in the first MAC entity,   wherein the PHR MAC CE comprises information regarding a difference between (i) a nominal UE maximum transmit power on a cell of the first MAC entity, and (ii) an estimated power for uplink transmission on the cell of the first MAC entity.